There is a phenomenal amount of information being shunted about inside us, carried either by electrical nerve signals or by chemical messengers such as hormones. All the disparate organs and structures of a human constitute a single organism because we are connected not just by resources, but by information, vast, coordinated, overlapping streams of it. Long before the “information age,” we ourselves were information machines.
That information falls into two categories. The first is the traveling information: nerve signals and chemical signals that are moving right now, seeping and flashing and flowing through us. But we also carry vast quantities of stored information, the molecular library that is filed away in our DNA. In the world around us, millions of similar atoms clump together to form large agglomerations of glass or sugar or water. But in the giant molecule that is a DNA strand, each minute atom sits in its prescribed place, and the precise placing of individual atoms of different types gives our bodies an alphabet. A piece of the cell’s molecular machinery can walk along the strand, reading the genetic alphabet of A, T, C, and G, and use that information to build proteins or regulate the activity of the cell. We have to be gigantic compared with atoms because each factory-like cell has to contain so much.
Our bodies are immense machines; even a single cell might contain a billion molecules, and there are around ten million million (1013) cells in our body. We need impressive signaling and transport systems to coordinate all these constituent parts, and that coordination takes time. No human has “lightning reactions,” because the cost of our wonderful complexity is the huge amount of time it takes us to get anything done. The shortest time that we can appreciate is approximately the blink of an eye (about a third of a second), but in that time millions of proteins have been built inside us and billions of ions have diffused across our nerve synapses, while the simpler world outside our bodies has just been getting on with things.
Our internal information engine carries on churning as we walk from one room to another. But this gigantic system needs information about what’s around it. Just at this moment, we need to find water. We have sensors built in, body parts that change in response to the environment and share that information with our brain. The sense that we’re most aware of is probably our sight.
We live submerged in light, but our body keeps most of it out. That sea of light carries information about the world, because light’s nature offers clues to its origins, but most of this information goes straight past us. A tiny fraction of this luminous cornucopia falls on to the pupils of our eyes, two circles at most 0.1 inch in diameter. A small subset of what arrives at the pupils, the visible light rays, is allowed in. From this tiny sample comes all of the visual richness that we take for granted. As they cross the boundary, these light waves must be marshaled so that the information can be harvested. Our windows on the world are guarded by soft, transparent lenses which slow the light to 60 percent of its speed in air. As these light rays are slowed down, they swerve, and the lens shape is tweaked by tiny muscles to make sure that all the rays from a single object out there, outside the body, will meet again at the back of the eye. This selection process is astonishing. We assume we see all there is, but really we sample only the tiniest fraction of what is out there to build our picture.
The light rays hitting our retina may have traveled from the Moon or from our fingers, but they have the same effect. A single photon is absorbed by a single opsin molecule, twisting the molecule around to start a chain of dominoes that sends an electronic signal into our control systems. As our thirsty body walked into the kitchen, photons that had bounced off a sink, a tap, and a kettle were streaming into our eyes, and our brain processes that information in the blink of an eye to tell us what to pick up first. If it’s slightly dark in the kitchen, we turn on a light bulb, releasing a fountain of light waves. They radiate outward, and as soon as their journey starts they’re being modified by the world, reflected, refracted, and absorbed until perhaps our eyes pick up what’s left. And it isn’t just light that’s flowing around us.
Humans are sociable animals. We hold our social networks together via communication, sending and receiving signals from others. Our voice is one of our most special features, a flexible musical instrument capable of producing and shaping sound waves which are then broadcasted through our surroundings. No Brit could imagine making a hot drink without asking others in the room whether they wanted to share the experience, and we ask with sound. The others in the room pick up the signal with their ears, and hearing the question will trigger a new flow of information inside their bodies, splitting and rejoining and gathering meaning until their nerve fibers instruct their vocal muscles to provide the appropriate response. Once the message has come back to us, we alter the world appropriately, rearranging the ceramics and metals in front of us.
Many different atoms make up our bodies, and wonderful though the variety is, there are limits to what we can do directly because of the way those atoms are arranged. But humans are experts at manipulating the world to produce tools that can do what we can’t. We can’t hold water in our hands as it boils, but a steel kettle can. We can’t turn a part of ourselves into an air-proof container for dried leaves, but a glass jar will do that job. We don’t have claws or a shell or tusks, but we can make knives and clothes and can openers. A ceramic container can hold a hot drink for us without transmitting the heat energy to our vulnerable and sensitive fingers. Metals, plastics, glass, and ceramics are all our proxies in the world, helped by the materials with biological origins: wood, paper, and leather.